Pipette control means



O MAISCH PIPETTE CONTROL MEANS July 14, 1953 2 Sheets- Sheet 1 Filed Aug. 29, 1951 16 1; I rfl'l II:

iliili' iill fizz/ en fan: 6464 M v fir Ff July 14, 1953 o. MAISCH PIPETTE CONTROL MEANS Filed Aug. 29, 195i 2 Sheets-Sheet 2 flflfarngg Patented July 14, 1953 UNITED STATES PATENT orrics 2,645,245 PIPETTE CONTROL MEANS- Oliver Maisch, Chicago, Ill. Application August 29, 1951, Serial N 0. 244,250

The primary object of the present'invention is to make it possible automatically to dispense successive, accurately measured volumes of various liquid materials.

In a specific sense my invention may be reslide or cam bar that actuates the other slide; garded as having for itsobject to control the and Fig. 8 is a more or less diagrammatic view pumping of liquids so that, using a continuously illustrative of an automatic time controlled sysoperating pump, accurately measured volumes or tem of which the valve device forms part1: units are dispensed automatically andin such a Referring to Figs. 1-7 of the drawings, I rep manner that the handling of the dispensed liquid resents a sturdy, box-like base upon-which stands is simple and easy and the opportunity for error a tall, slab-like block 2. The block maybe fasdue to human frailty is negligible. tened'to the base in any suitable way as, for ex- In carrying out my invention I employ a pump ample, by bolts 3 extending up into the same the speed of which may be controlled to cause through the top wall of thebase, as shown in the pump to discharge any desired'volume of Fig. 1. v I liquid, accurately measured, in a given period In the front side of block 2 are-two wide, in of time. The outlet from the pump is through tersecting slots 4 and 5 ,slot 4 being horizontal two flexible tubes or pipettes, one of which conand slot 5 being vertical and centrally; located stitutes the dispensing line while the other is a with respect to the block. Slot 4 is deeper than bypass line leading back to the intake side of the other slot. 3 the pump. Then, with the pump running con- Within and slidable in slot 4 is a bar 6 the tinuously, by alternately pinching or collapsing thickness of which equals the depth of that slot the pipettes to stop flow therethrough, liquid may and which is a little longer than the width of the be caused to flow through either, but not through block. In the front face of bar 6, midway be-; both at the same time. tween the ends thereof, is a recess '1' somewhat A further object of the invention is to pro- Wider than and of the same depth as slot 5. Axduce a simple, novel, reliable and eflicient means ially arranged, nose-like lugs 8 and 9 protrude for effecting the collapse and subsequent release into the recess with their tips spaced apart'a of each pipette in a manner and at times deterdistance substantially less than the width of slot mined by the end results sought. 5. When bar 6 is in its slot it fills the same and In order that measuring of dispensed liquids its recess 1 bridges the gap in slot 5 at the intershall be accurate, the changes in the conditions section of the two slots. j I of the pipettes must take place instantaneously. Within slot'5 is a long, fiat bar H), as wide a Therefore, in oneaspect of my invention, it may and having a thickness equal to the depth of the be said to have for an object to produce a simple 5 slot. In the long edges of bar iii are two long, and novel mechanism which, in cooperation with deep, reversely arranged cam notches l l and 12 two pipettes, forms, in efiect, a compound, snapthat are displaced relative to eachother lengthaction control valve. a wise of the bar but in overlapping relation ito The various features of novelty whereby ,the a other- These h are s ap d that present invention is characterized will herein- .wthe reduced neck portion [4 of the bar, separatafter be pointed out withparticularity in the ing the cam notches, fits slidably between the claims, but, fora full understanding of the intips of lugs 8 and 9. I In the particular arrangevention and of'its objects andadv antages, referment illustrated, When either lug is inthe deep ence may be had to thefollowing detailed deend of the correspon ing notch, the other lug is scription taken in connection with the accomengaged with an unmutilated portion .ofv the panying drawings, wherein:

Figure l is a front view of avalve deviceem-y bodying the present invention, portions of the casing being omitted and two pipettes therein being shown in section; Fig. 2 is a side view'of 7 Claims. (Cl. 137-569) a perspective view of the horizontal, pinching slide; Fig. 7 is a perspective view of the vertical edge of the cam. bar just beyond the shallow end of the other cam notch.

There is a thick cover plate IS on the front side of block 2, held in place by screws It, to

keep bars 6 and 10 in their respective slots, while device; Fig. 5 is a perspective viewof the sup porting block for the two crossing slides; Fig. 6 is face is a deep well l9 within which is located a long compression spring 20 which, when expanded. reaches to the top of elements [1. On the upper end of cam bar In is a rearwardly directed horizontal flange or lip 2| that overlies the spring and is provided with a pin 22 that enters and centers the spring. The initial compression of the spring may be varied by a screw 24 extending up into the block and serving as an adjustable support for a small follower disk 25 which constitutes the immediate support for the lower end of the spring.

The lower end of cam bar In extends down through the top wall of the base and is there connected with the movable core or armature 25 of a solenoid or electromagnet 26.

The parts are so proportioned that when the solenoid is energized the cam bar is held in its down position, as shown in full lines in the drawings; whereas the springat all other times holds the-bar up as indicated in dotted lines in Fig. 4. Fixed-to the opposed side edges of block -2 are two similar brackets 21 and 28, each having a part facing but spaced apart from the corresponding end of'bar or slide 6. Each bracket is provided with a screw 29 axially aligned with this bar and having on its inner end a head or anvil 30. By adjusting the screws the anvils may be moved closertoorfarther apart from each other.

In using the device, two flexible tubes or pipettes, B and C, are placed on the brackets, each between one of the anvils and the adjacent end of slide 6. The parts are so adjusted that, when, either of the tubes retains its normal shape, the other tube is pinched shut or collapsed between the adjacent anvil and the adjacent end. of the horizontal slide or pinch bar 6. Thus, by employing a strong spring and a powerful electromagnet, andalternately energizing and deenergizing the latter, the device serves the same purpose as a snap-action valve in each of the tubes or pipettes.

The tubes are prevented. from jumping out of their seats by pins 3 I, projecting from the side edges of block 2 partway across such'seats.

Fig. 8 illustrates apipette. control system in which the pipette pinching apparatus is advantageouslyemployed. In this systemP is a motor driven precision pump having an inlet conduit A and a discharge conduit B through which liquid is pumped and dispensed. C is a bypass connecting the intake conduit to the outlet conduit at a point near the pump. All three conduits may be soft rubber tubes, although only conduits B and C, or sections thereof, need be flexible.

T is a timer for controlling the electromagnet, the terminals of the latter being connected to the timer by a cable 32; and the timer being provided with a cable 33 to plug the same into a power circuit.

Tubes, orpipettes B, and C are inserted in the valvedevice as heretofore explained. Since the electromagnet is deenergized, the cam bar is up as shown in broken lines in Fig. 4. The user can depress the cam bar by pressing down on lip or flange 2|, on the upper 'end of the cam bar, to facilitate the insertion of the tubes in the pinching or clamping means.

With the electromagnet still deenergizecl, the discharge tube B is in a collapsed state, while bypass tube C is wide open, as in Fig. 8. Therefore thepump may be started, but will only idle, circulating the liquid through the bypass, with none flowing past the collapsed or pinched section of discharge tube B.

Assuming that it is desired to dispense accurately measured quantities of liquid into bottles, for example, the timer is set to allow the electromagnet to remain energized for the exact length of time required by the pump to pump the quantity of liquid desired in a single unit.

With the timer in operation, it first causes the electromagnet to be energized, sothatthe cam bar is drawn down abruptly. This causes the pinch bar to snap into the position opposite that occupied thereby in Fig. 8; thereby suddenly collapsing the bypass tube and allowing the discharge tube to resume its normal shape. A bottle having been placed in position to receive liquid from the discharge tube, the filling of the bottle starts immediately. This condition is maintained until the timer interrupts the flow of current to the electromagnet, allowing the spring to come into action and restore the conditions existing in Fig. 8, with the discharge tube pinched shut and the bypass open to allow the pump to idle.

If many bottles are to be filled, the timer may be set to energize and deenergize the electromagnet alternately in automatic succession, with periods of deenergization only long enough to enable the operator toremove each bottle and replace it by its successor. However, the means for determining whata, cycleshall be, or whether cycles shall automatically repeat themselves, depend on the need in any given use, and may vary widely.

While I have illustrated and described with particularity onlya single preferred form of my invention, I do not desire to be limited to the exact details thus illustrated and described, but intend to cover all forms and arrangements that come within the definitions of my invention constituting the appended claims.

Iclaim:

1. In a pipettingcontrol device, a stationary support, a pinch bar slidable lengthwise in said support, anvils mounted on the support in alignment with and beyond the ends of the pinch bar, the pinch bar having at the middle two lugs spaced apart lengthwise of the bar, a fiat, twoposition cam bar, wider than the distance between said lugs and having in opposite edges long cam notches displaced somewhat relatively to each other lengthwise of the cam bar, said cam bar being mounted on said support so as to lie between said lugs with either lug being in the deepest portion of the corresponding cam notch and slidable lengthwise, an electromagnet connected to one end of the cam bar to move it into one of its said positions, and a compression spring parallel to the cam bar and resting .at one end on said support and engaged at its other end with the cam bar and tending constantly to hold it in its second position.

2. In a pipetting-control device a stationary support, a pinch bar slidable lengthwise in said support, anvils mounted on the support in alignment with and beyond the ends of the pinch bar, the pinch bar having at the middle two lugs spaced apart lengthwise of the bar, a flat, twoposition cam bar, wider than the distance between said lugs and having in opposite edges long cam notches displaced somewhat relatively to each other lengthwise of the cam bar, said cam bar bein mounted on said support so as to lie between said lugs with either lug being in the deepest portion of the corresponding cam notch and slidable lengthwise from one of its positions support, a pinch bar slidable lengthwise in said,

support, anvils mounted on the support in alignment with and beyond the ends of the pinch bar, the pinch bar having at the middle two lugs spaced apart lengthwise of the bar, a flat, twoposition cam bar, wider than the distance between said lugs and having in opposite edges long cam notches displaced somewhat relatively to each other lengthwise of the cam bar, said cam bar being mounted on said support so as to lie between said lugs with either lug being in the deepest portion of the corresponding cam notch and slidable lengthwise, the movable member of an electromagnet connected to one end of the cam bar, said support containing behind and parallel to the cam a deep well, a compression spring in and resting on the bottom of the well, and a lip on the second end of the cam bar extending over the second end of the spring and holding it at all times under compression.

4. In a pipetting control device, a support, brackets on the exterior and at opposite sides of said support, a transverse pinch bar slidably mounted on the support between and aligned with said brackets, an element mounted'on each bracket so as to be adjustable from and toward the pinch bar and serve as an anvil cooperating with the latter to collapse an elastic tube inserted between them, a cam bar mounted on the sup-.

port for lengthwise sliding movements crosswise of the pinch bar, a spring mounted on the support adjacent to the cam bar and engaged with the latter to move it lengthwise in one direction, an electromagnetic actuator on the support and connected to the cam bar to move it in the opposite direction, and cooperating camming devices on said bars to cause the pinch bar to move back and forth in coordination with the cam bar.

5. In a pipetting control device, a support comprising a hollow base member and a secondmember rising therefrom, brackets on the exterior and at opposite sides of said second member, a transverse pinch bar slidably mounted on said second member between and aligned with said brackets, an element mounted on each bracket 6 P u so as to be adjustable from and toward the pinch bar and serve as an anvil cooperatingwith the latter, to collapse an elastic tube placed between them, a cam bar mounted on saidsecond member for lengthwise sliding movements crosswise of the pinch bar, a spring mounted onsaid second member adjacent to and engaged with the cam bar to move it lengthwise in one direction, an electromagnetic actuator housed in the base member and connected to the cam barto move it in the direction opposite to theaforesaid direction, and cooperating camming devices on said bars to cause the pinch bar to move back and forth in coordination with the cam bar.

6. In a pipetting control device, a support comprising a hollow base member and a second member rising therefrom, brackets on the exterior and at opposite sides of said second member, a transverse pinch bar slidably mounted on said second member between and aligned with said brackets, an element mounted on each bracket so as to be adjustable from and toward the pinch bar and serve as an anvil cooperating with the latter to collapse an elastic tube placed between them, a cam bar mounted on saidsecond member for lengthwise sliding movements crosswise of the pinch bar, said second member containing a chamber behind and parallel to the cam bar, a spring in said chamber and engaged with the cam bar to move it in one direction, an electromagnetic actuator housed in the base member and connected to the cam bar to move the latter in theopposite direction, and camming devices on said bars cooperating with each other to cause the pinch bar to move back and forth in coordination with the cam bar.

7. In combination, a continuously operating pump having an intake, an elastic'delivery tube connected to the discharge-side of the pump, an elastic, tubular bypass connecting the delivery tube to said intake, means acting on said bypass and said delivery tube at a point beyond the bypass, alternately to pinch one of them to stop flow therethrough while a free flow through the other is maintained, and a timer controlling the said meansto determine the time intervals between successive pinchings. I

' OLIVER MAISCH.

References Cited in the file of this patent UNITED STATES PATENTS Grove June 12, 1951 

